Restoring original visitor IP address in cloudflare is easily done by utilizing the header CF-Connecting-IP header.
Cloudflare being the fastest Free DNS provider and one of the most commonly used CDN(Content delivery network). Most of us use cloudflare as the primary dns provider instead of using the dns service provided by the domain registrar.
So when we use cloudflare as the primary dns provider and have the traffic served through cloudflare proxy it helps in masking the original ip address of the server, thereby hiding the original service provider.
This is a very useful feature provided by cloudflare DNS which is available even in the free plan where the cloudflare will protect your website and server from bots and only pass clean traffic to your servers.